The concepts of fluid and rigid boundaries were assessed in an improvisational role-playing task in an attempt to differentiate paranoid from nonparanoid schizophrenics. Thirty-one schizophrenic patients divided into paranoid, intermediate, and nonparanoid groups were given an improvisational role-playing task. The resulting scenes were analyzed by Fluid Boundary and Rigid Boundary scales, which were developed on the basis of specific aspects of the physical and verbal representations of characters, objects, and settings. The hypothesis that variations in the disruption or emphasis of representational boundaries differentiate paranoid and nonparanoid symptomatology received support. Paranoid schizophrenics scored higher on the Rigid Boundary scale, i.e. erecting and/or exaggerating physical and interpersonal boundaries; and nonparanoid schizophrenics scored higher on Fluid Boundary scale, i.e. showing fused and fluid representations of characters, objects, and settings. Improvisational role-playing seems to hold promise as a medium with diagnostic value. ABSTRACT FROM AUTHOR